This invention relates to control knobs for irregularly shaped rotatable shafts, and more particularly relates to knobs for electrical controls having rotatable D-shafts.
Electrical or other controls, such as volume controls or switches which control various means in response to rotation of the control shaft, generally have a manually rotatable control knob on the end of the control shaft. It is often desirable to removably mount the knob on the end of the shaft while maintaining full rotational force fit between the knob and the shaft, as well as longitudinal friction fit. For example, when the knob is disposed on one side of a control panel and the control means is on the other side of the panel, it is necessary to remove the knob in order to remove the control panel.
The control knob preferably is removed axially off of the end of the shaft. Heretofore, the knob most often was held onto the shaft by a separate spring member, such as a metal leaf spring, which was mounted by other means in or around the aperture in the knob. The separate spring member also has been at times molded in position within the knob by providing a special molded cavity which receives and positions the spring member prior to molding the knob thereabout. The present invention obviates these multiple parts and multiple molding steps by providing a unitarily molded control knob which receives the control shaft and has a unitarily molded resilient cantilever arm which yieldably biases the control shaft against an opposing flat.
A flat in the receiving means of the knob engages the flat of the D-shaft to prevent relative rotation between the knob and the shaft, and the spring biasing of the cantilever arm between the knob and the shaft releasably holds the knob longitudinally onto the shaft.
While this invention is susceptible of embodiment in many different forms, it is shown in the drawings and will hereinafter be described in detail a specific embodiment thereof, with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.